Aum

The primary symbol of Hinduism is the Aum (or Om), a Sankrit syllable that first appears in the Upanishads. Aum has been seen as the first manifestation of the unmanifest Brahman (the single Divine Ground of Hinduism) that resulted in the phenomenal universe. Essentially, all the cosmos stems from the vibration of the sound "Aum" in Hindu cosmology. Indeed, so sacred is it that it is prefixed and suffixed to all Hindu mantras and incantations. Full article...